Moisture Evaporation Research Articles

Fractal Characteristics of Natural Fiber-Reinforced Soil in Arid Climate Due to Cracking

Fractal geometry is a geometry that focuses on irregular geometric forms and can quantitatively describe rough and uneven surfaces and interfaces. As the main material for making natural fiber geotextile, rice straw fiber can reduce the direct impact of rainfall on soil and reduce the intensity of hydraulic erosion. This study investigates whether the use of rice straw fiber as an additive to reinforce arid soil can inhibit moisture evaporation and prevent cracking. Samples with different fiber contents added (0%, 1%, 2%, and 4%) are placed in an environmental chamber to simulate the effects of an arid climatic condition and control the temperature and humidity levels. The cracking process of the samples is recorded by using a digital camera, and the parameters of the evaporation and cracking processes are quantitatively examined through digital image processing. The results show that all of the samples with fiber have a higher residual water content and can retain 31.4%, 58.5%, and 101.9% more water than without the fibers, respectively. Furthermore, both the primary and secondary cracks as well as crack networks are inhibited in samples with a higher fiber content, that is, 2% or 4% fiber contents. The samples reinforced with fiber also have a smaller crack ratio. Compared with the samples without straw fiber, the final crack ratio of the samples with 1%, 2%, and 4% fiber is reduced by 8.05%, 24.09%, and 35.01% respectively. Finally, the final fractal dimensions of the cracks in samples with fiber contents are also reduced by 0.54%, 5.50%, and 6.40% for the samples with 1%, 2%, and 4% fiber, respectively. The addition of natural fiber as an additive to reduce evaporative cracking in soil can: (1) reduce the soil porosity; (2) enhance the binding force between the soil particles; and (3) block the hydrophobic channels. Therefore, the addition of rice straw fiber to soil can effectively reduce soil evaporation and inhibit soil cracking.

Coaxial electrospun PVA-SAP functional nanofibers embedded with betel leaf extract for enhanced germicidal activity and breathability

This study investigates the formation of coaxial electrospun nanofibrous membrane with enhanced germicidal activity and breathability using superabsorbent polymer and polyvinyl alcohol integrated with betel leaf extract and its utilization for developing performance textiles. The functional nanofibrous membrane was fabricated through the coaxial electrospinning technique and characterized for the intended applications. The morphological investigation of the developed nano-membrane using scanning electron microscopy revealed the formation of regular nanofibers with diameters ranging from 154 to 200 nm. The FTIR spectra suggested the existence of functional compounds in the nanofibers from their characteristic peaks. The presence of the bioactive compounds in the ethanolic extract of betel leaf was explored using phytochemical screening. The analysis of antibacterial activity against S. aureus and E.coli using the agar disc diffusion method showed an enhanced zone of inhibition with a maximum dimension of 27 mm and 24 mm against S. aureus and E.coli, respectively. The developed coaxial nanofibrous membranes also demonstrated acceptable particle barrier performance with greater than 95 % efficiency and a superior tensile strength of 99.5 N. Besides, the improved moisture management and air permeability of coaxial nano-membranes embedded with betel leaf extracts suggested an easy transfer of fluid and moisture vapor from the body to the environment via the membrane. Hence, the improved germicidal activity with acceptable particle filtration efficiency and enhanced breathability of the developed coaxial electrospun nano-membranes indicated their potentiality of utilizing them in designing performance textiles with simultaneous barrier performance and breathability for comfort.

Composite hydrogels fabricated from konjac glucomannan and gellan gum: Rheological characterization and their potential application in sustainable agriculture

In this study, konjac glucomannan (KG) was incorporated in high acyl gellan (HAG) and low acyl gellan (LAG) hydrogels in different ratios. The addition of KG increased pseudoplasticity and thermal hysteresis values of the hydrogels. Improvement in elasticity and water holding capacity (WHC) was observed in KG-LAG hydrogels. The highest WHC (98.5 %) was observed for 1K1H (KG:HAG = 1:1) and 3K7L (KG:LAG = 3:7) hydrogels. The crystallinity of the composite hydrogels was lower than hydrogels prepared from individual biopolymers. The hydrogels exhibited a rough surface with minute pores in the cross-section, due to the aggregation of glucomannan on the gellan network in the composite hydrogels. While HAG and 1K1H hydrogels exhibited greater swelling at low pH (3.0), LAG and 3K7L exhibited greater swelling at high pH (11.0). At pH 7.0, the hydrogels exhibited swelling indices >300 %. Incorporation of 1K1H hydrogel at 10 % (w/w) in sandy loamy soil under semi-arid conditions increased the germination of fenugreek microgreens from 60 % to 80 % on the 15th day. Furthermore, the moisture evaporation rate of the soil reduced from 35 % to <15 %, positively impacting the physicochemical properties of the microgreens. The composite hydrogels were successful in achieving a controlled release of phosphate fertilizer.

Oxide‐based ternary composite solid‐state electrolyte for next‐generation lithium batteries

AbstractOxide‐based solid electrolytes are gaining popularity among researchers owing to their great structural stability. In this work, a novel oxide‐based ternary composite (AlPO4‐SiO2‐Li4P2O7) electrolyte is synthesized via a conventional solid‐state process with excellent water stability and high ionic conductivity. The crystallographic structure of ternary composite is confirmed using x‐ray diffraction and has a significant effect on ionic conductivity. The thermogravimetric analysis result shows a 22.26 wt% loss in the region of 25°C to 900°C due to the evaporation of volatile constituents, including nitrates, carbonates, and moisture. Surface analysis results revealed compact morphology and low porosity with arbitrary grain sizes. Electrochemical impedance spectroscopy has been used to evaluate ionic conductivities. The Mn‐ternary composite sintered at 900°C has shown ionic conductivity of 1.63 × 10−6 S/cm at ambient temperature. 8 wt%‐LiBr enhanced the ionic conductivity up to 1.68 × 10−4 S/cm by significantly reducing the grain boundaries without high‐temperature sintering. Results suggested the suitability of LiBr mixed ternary composites as a favorite candidate for lithium batteries in terms of safety, stability, and high ionic conductivity.

Water loss and shrinkage prediction in 3D printed concrete with varying w/c and specimen sizes

In 3D printed concrete (3DPC), the absence of formwork leads to increased shrinkage compared to traditional cast concrete which uses formwork. This increase in shrinkage is primarily due to the rapid evaporation of moisture during the early stages. Therefore, our research focused on how the initial water content and the exposed surface area affect the total shrinkage by varying water-to-cement ratio (w/c) and the surface-to-volume ratio (s/v). For 3DPC with high w/c, we used calcium formate (CaF) to improve its printability by increasing static yield stress. Dry environment makes the evaporation the predominant mode of water loss, significantly decelerating the hydration process in samples with fully exposed surfaces. At 28 d, the evaporated moisture in 3DPC is 2.8 times higher than the moisture consumed by hydration. A predictive model for the shrinkage properties of 3DPC has been developed by considering that 3DPC experiences both hydration and evaporation simultaneously from early stages on the basis of the water mass conservation principle. The predictions were found to align with actual shrinkage test results, as evidenced by quantitative analysis of parameters like internal RH, mass loss, degree of hydration, and porosity, thus validating the accuracy of the model.

Перспективные конструкторские решения для сушки жидких пищевых систем

An assessment of promising alternative design solutions for drying liquid food systems is given. Drying technology and techniques for removing moisture from liquid materials in a dispersed state have found widespread use in the food industry. The almost instantaneous drying of the sprayed particles in the coolant flow causes the formation of a developed phase interaction surface and acceleration of heat and mass transfer procedures, as well as the exclusion of overheating of the material due to intensive volumetric evaporation of moisture. A number of dryer designs have been developed to eliminate disadvantages (such as the large size of the dryers and their relatively high energy consumption and complexity of structural elements) or to reduce their impact on the course of the dehydration operation. The design specifics of devices for dewatering in the atomized state are due to the methods of supplying thermal energy, technological conditions and limitations, parameters of the dried product and the final powder substance, as well as its specific yield, peculiarities of the spraying operation, etc. The justification of the method of spray drying of liquid food material and the constructive use of the apparatus should be based on the study of a set of parameters and characteristics of the dehydration object, as well as on the construction and solution of a mathematical model of heat and mass transfer and exchange processes at the boundary of the phase section, as well as their mechanism in the development of a rational method of moisture removal to ensure the quality of finished products and energy- and resource saving. The proposed plant designs are recommended for organizing the drying process of liquid products, in particular for drying broths in fish production technologies.

ХРАНЕНИЕ ТОМАТОВ – ТРАДИЦИОННЫЕ И ПЕРСПЕКТИВНЫЕ ТЕХНОЛОГИИ

As known, tomatoes contain a fairly large amount of biologically valuable substances in their composition. Consumers prefer tomatoes in fresh form. However, being a climacteric crop, tomatoes differ during storage and maturation by a high rate of respiration and evaporation of moisture, which leads to a decrease in valuable nutrients, deterioration in quality, over-ripening and rapid aging, which as a result reduces the marketable appearance of products. Traditional methods of processing tomatoes before storage are not always effective enough to maintain the quality of tomato fruits at the proper level, since it is not always possible to store tomatoes at the recommended low temperature, the necessary relative humidity, etc. In order to increase the storage time of tomatoes while maintaining their quality and safety, it is necessary to search for new modern methods of fruit processing before storage. In this regard, an overview of existing traditional technologies, as well as modern and promising techniques and methods for preparing fresh tomatoes for storage, contributing to the reduction of quantitative losses, preserving qualitative characteristics, is carried out. The most promising methods of preliminary preparation of tomatoes for storage, providing a high level of physical-chemical, organoleptic and microbiological indicators that ensure the safety of stored products are: treatment with ethylene biosynthesis inhibitors and ethylene absorbers, ozonation, modified gas atmosphere, electric field and ultrasound treatment, the use of biological products, the use of active packaging, antimicrobial film-forming coatings, etc. The article describes the work of both domestic and foreign researchers. Keywords: FRESH TOMATOES, PROCESSING, STORAGE TECHNOLOGY, QUALITY

A study on ecohydrological mutual feedback relationship of the Shangdong River basin based on hydrological connectivity

Investigating eco-hydrology in desert grasslands is pivotal to comprehend the dynamic evolution patterns of vegetation. Nonetheless, a research void persists in understanding the eco-hydrological mutual feedback mechanisms associated with hydrological connectivity and the corresponding health index evaluation of a small watershed. This study is centered on the Shangdong River watershed in Inner Mongolia and uses SWAT (Soil and Water Assessment Tool) to simulate hydrological processes. The hydrological connectivity index (IC) was employed as a link to conduct Pearson correlation analysis and Granger causality tests on ecological and meteorological-hydrological factors. Additionally, the PSR model was utilized to assess the ecological health status of the watershed. Key findings reveal the following: (1) The NDVI in the Shangdong River watershed showed an overall upward trend from 2007 to 2018, while IC exhibited an overall downward trend. Temporally and spatially, there was a significant negative correlation between IC and NDVI. (2) During the vegetation growth season, IC serves as a pivotal link in the feedback loop of eco-hydrological processes. Temperature drives vegetation growth, which in turn affects IC. IC regulates soil moisture content and evaporation, further influencing vegetation growth, thus forming a feedback mechanism. (3) Over the study period, the Grassland Health Composite Index (GHI) demonstrated a consistent rise, averaging 0.44, signaling a suboptimal state for the grassland ecosystem. Furthermore, a negative correlation was observed between GHI and IC. Consequently, regulating IC could play a crucial role in safeguarding and rejuvenating the grassland ecosystem. This study offers theoretical and data support for understanding eco-hydrological processes and effective pasture management of the desert grassland watershed.

Thermal Decomposition and Combustion Analysis of Malaysian Peat Soil Samples Using Coats Redfern Model-free Method

This research investigates the thermal decomposition behaviour of Malaysian peat soil through thermogravimetric analysis at varying heating rates. The study aims to analyse the thermal kinetics of decomposition for distinct peat soil types under inert and oxidative atmospheres while considering the role of available oxygen. The investigation encompasses virgin and agricultural peat, employing a non-isothermal thermogravimetric analysis technique to evaluate thermal decomposition characteristics and compute kinetic parameters using the Coats Redfern model-free approach. The pyrolysis profiles reveal three primary stages: moisture evaporation (30–180°C), organic component decomposition (200–500°C), and mineral decomposition (600–800°C). Virgin peat experiences a 43% mass loss during pyrolysis, while agricultural peat shows a 46% mass loss, emphasising insights into thermal behaviour and consistent decomposition patterns across peat types. Combustion profiles exhibit three main stages: dehydration (30–180°C), oxidative pyrolysis transforming organic matter into volatiles and char (200–300°C), and subsequent char oxidation (300–500°C). The study determines average activation energy trends, measuring 14.87 kJ/mol for virgin peat and 5.37 kJ/mol for agricultural peat under an inert atmosphere, and 28.89 kJ/mol for virgin peat and 36.66 kJ/mol for agricultural peat under an oxidative atmosphere. The research introduces an innovative two-step reaction model elucidating peat thermal decomposition kinetics (excluding dehydration), including a discussion on the impact of oxygen availability on kinetic parameters. These findings essential peat fire smouldering modelling, contributing to peat combustion behaviour for effective strategies to reduce peat fire risks.

Rheological Performance Analysis of Different Preventive Maintenance Materials in Porous High-Viscosity Asphalt Pavements.

Porous asphalt pavements are widely used in rainy and wet areas for their skid resistance, noise reduction, runoff minimization and environmental sustainability. Long-term moisture vapor erosion and the destabilization of large pore structures can easily result in pavement problems such as fragmentation, spalling, cracking, and excessive permanent deformation. To this end, four different preventive maintenance materials, including the rejuvenation (RJ), cohesion reinforcement (CEM), polymerization reaction, and emulsified asphalt (EA) types, were selected in this paper to improve the high-viscosity porous asphalt pavement. The effects of the different preventive maintenance materials on the temperature sensitivity, rheological properties and fatigue performance of high-viscosity modified asphalt were evaluated through temperature sweep, frequency sweep, multi-stress creep recovery (MSCR), linear amplitude sweep (LAS), and bending beam rheometer (BBR) tests. The results showed that the four preventive maintenance materials exhibit different enhancement mechanisms and effects. RJ improves the fatigue properties, deformation resistance and low-temperature cracking resistance of aged asphalt by adding elastomeric components; CEM materials are more conducive to increasing the low-temperature crack resistance of aged asphalt; while GL1 and EA improve the viscoelastic behavior of aged asphalt, but the effect of the dosing ratio needs to be considered.

Study on indoor air temperature and moisture behaviour in historical churches

Increased indoor air humidity in cultural heritage buildings in the Baltic States region results in the deterioration of cultural heritage values. Existing norms, standards, and research do not specify the necessary conservational microclimate indoor air parameter limits. Two main types of historical cultural heritage building constructions exist based on enclosing structures – wood and masonry, with various heating strategies and usage intensities. This study complements previous research on the microclimate of Krimulda Church and compiles measurements of three additional Latvian churches: Turaida Church, Riga Jesus Church, and Liepaja St. Trinity Cathedral. Microclimate measurements were conducted in two wood and two masonry churches. Humidity ratio and moisture excess calculations were derived from the measurement data. Results indicate that in certain cases, the moisture excess threshold of 6 g/m3 and indoor air humidity ratio threshold of 15,6 g/kg are exceeded, posing a significant risk of condensation. Moisture evaporation levels from masonry church constructions were identified. The study reveals conservational microclimate indoor air parameter limits for various types of churches in the Baltic States climatic region.

Drying kinetics and mathematical modeling of seeds of two mango varieties at different temperatures and with different pretreatments

AbstractIncreasing global waste generation is not only a threat but also an opportunity to address energy insecurity and pollution using green valorization techniques. However, this requires pretreatment of waste and byproducts and optimization of drying to obtain high‐quality biofuels. Hence, this study aims to analyze the performance of currently used drying models, the influence of different drying temperatures, drying time, and seed pretreatment on the drying kinetics of two varieties of mango seed. Accordingly, whole seeds and crushed seeds were exposed to five drying temperatures (313–353 K) in a heating furnace. Weight loss was recorded systematically, converted into moisture ratio, and then fitted to four semitheoretical mathematical models, namely: (i) Lewis, (ii) Henderson and Pabis, (iii) Page, and (iv) Avhad and Marchetti models. The fitness of these models was compared using statistical parameters, such as R2, X2, root mean square error (RMSE), mean bias error (MBE), and mean absolute error (MAE). The results showed that seed pretreatment and increasing the drying temperature led to an increase in the rate of moisture evaporation and reduced the time required for drying. Among all models, the Avhad and Marchetti model provided higher R2 values of 0.9994 and 0.9991 for local and hybrid mango at 313 K, and 0.9977, and 0.9970 for local and hybrid crushed mango seeds at 353 K and 313 K, respectively; hence, it showed the best performance. The activation energy (Ea) showed a slight differences for both varieties of mango seed and among pretreatments in all mathematical models. The mean Ea values for local and hybrid mango seeds were 41.18 kJ mol−1 and 46.21 kJ mol−1, respectively. For whole and crushed local and hybrid mango varieties, the mean Ea values were 31.37 kJ mol−1, 40.80 kJ mol−1, 50.99 kJ mol−1, and 51.61 kJ mol−1. The likely reason for this variation might be differences in variety, chemical composition, growing conditions, and cellular structure of the seed varieties.

Analysis of the Solar Pyrolysis of a Walnut Shell: Insights into the Thermal Behavior of Biomaterials

The state of Sonora, Mexico, stands as one of the leading producers of pecan nuts in the country, which are commercialized without shells, leaving behind this unused residue. Additionally, this region has abundant solar resources, as shown by its high levels of direct normal irradiance (DNI). This study contributes to research efforts aimed at achieving a synergy between concentrated solar energy technology and biomass pyrolysis processes, with the idea of using the advantages of organic waste to reduce greenhouse gas emissions and avoiding the combustion of conventional pyrolysis through the concentration of solar thermal energy. The objective of this study is to pioneer a new experimental analysis methodology in research on solar pyrolysis reactors. The two main features of this new methodology are, firstly, the comparison of temperature profiles during the heating of inert and reactive materials and, secondly, the analysis of heating rates. This facilitated a better interpretation of the observed phenomenon. The methodology encompasses two different thermal experiments: (A) the pyrolysis of pecan shells and (B) the heating–cooling process of the biochar produced in experiment (A). Additionally, an experiment involving the heating of volcanic stone is presented, which reveals the temperature profiles of an inert material and serves as a comparative reference with experiment (B). In this experimental study, 50 g of pecan shells were subjected to pyrolysis within a cylindrical stainless-steel reactor with a volume of 156 cm3, heated by concentrated radiation from a solar simulator. Three different heat fluxes were applied (234, 482, and 725 W), resulting in maximum reaction temperatures of 382, 498, and 674 °C, respectively. Pyrolysis gas analyses (H2, CO, CO2, and CH4) and characterization of the obtained biochar were conducted. The analysis of heating rates, both for biochar heating and biomass pyrolysis, facilitated the identification, differentiation, and interpretation of processes such as moisture evaporation, tar production endpoint, cellulosic material pyrolysis, and lignin degradation. This analysis proved to be a valuable tool as it revealed heating and cooling patterns that were not previously identified. The potential implications of this tool would be associated with improvements in the design and operation protocols of solar reactors.

A novel CFD-DEM-DPM modelling of fluid-particles-fines reacting flows

The complex fluid-particle-fine (FPf) reacting flows have been widely practised in many energy-intensive engineering processes, yet numerical methods capable of comprehensively describing the particle-scale thermochemical behaviours related to the FPf reacting flows were still lacking. In this work, a novel CFD-DEM-DPM model is developed, for the first time, to describe the fluid, particles and fines reacting flows and their interactions. Then, to demonstrate its effectiveness, it is employed to simulate the co-combustion of coke and pulverized coal in a dynamic raceway in ironmaking blast furnaces (BFs). After model validation, the complex in-furnace phenomena related to the co-combustion of coarse coke particles and fine coal particles are comprehensively captured. Particularly, instead of the pre-set raceway treatment in the previous raceway simulations, a dynamic raceway cavity is predicted explicitly driven by the fluid-particle-fine interactions and further, inside the dynamic raceway, the combustion of coal fines including moisture evaporation, devolatilization and char reactions are presented in detail. Subsequently, the impact of operations with and without coal injections are quantitatively compared, showing that both the reducing gas and reaction heat from the coal combustion contribute to an expansion of the raceway cavity. Further, the effects of pulverized coal rate on the in-furnace phenomena are studied. The present work represents a significant breakthrough in the explicit modelling of FPf reacting flows, and provides a cost-effective tool for understanding FPf-related processes and developing new technologies including carbon–neutral ironmaking technologies.

Highly Sensitive Iontronic Pressure Sensor with Side-by-Side Package Based on Alveoli and Arch Structure.

Flexible pressure sensors play a significant role in wearable devices and electronic skin. Iontronic pressure sensors with high sensitivity, wide measurement range, and high resolution can meet requirements. Based on the significant deformation characteristics of alveoli to improve compressibility, and the ability of the arch to disperse vertical pressure into horizontal thrust to increase contact area, a graded hollow ball arch (GHBA) microstructure is proposed, greatly improving sensitivity. The fabrication of GHBA ingeniously employs a double-sided structure. One side uses mold casting to create convex structures, while the other utilizes the evaporation of moisture during the curing process to form concave structures. At the same time, a novel side-by-side package structure is proposed, ensuring pressure on flexible substrate is maximally transferred to the GHBA microstructure. Within the range of 0.2Pa-300kPa, the iontronic pressure sensor achieves a maximum sensitivity of 10420.8kPa-1, pressure resolution of 0.1% under the pressure of 100kPa, and rapid response/recovery time of 40/35ms. In wearable devices, it is capable of monitoring dumbbell curl exercises and wirelessly correcting sitting positions. In electronic skin, it can non-contactly detect the location of the wind source and achieve object classification prediction when combined with the CNN model.

Fracture characteristics and failure analysis of underground caverns in Longyou Grottoes induced by humidity change

The stability of underground caverns in Longyou Grottoes is greatly influenced by humidity change since they are mainly composed of argillaceous siltstone, which is highly sensitive to moisture. In this work, a coupled humidity diffusion-fracture model based on the finite-discrete element method (FDEM) is employed to study the fracture characteristics and failure mechanism of underground caverns No.4 and 5 in Longyou Grottoes caused by humidity change. Firstly, the input parameters are calibrated with uniaxial compression tests on dry and saturated siltstone samples. Then, the crack patterns of a disk rock specimen under drying and wetting conditions are captured, which are compared with experimental results to validate the coupled model and calibrated parameters. Subsequently, numerical models of caverns No.4 and 5 in the Longyou Grottoes are established based on the actual geological conditions. The failure processes of the surrounding rock under moisture evaporation and absorption are simulated, and the stress evolution caused by humidity change is analyzed. Results indicate that the caverns primarily experience tensile failure under the evaporation condition with a distribution of tensile cracks perpendicular to the cavern boundary. However, shear failure occurs in the surrounding rock during moisture absorption, and the cracks gradually propagate into the deep rock with humidity diffusion. Additionally, several factors influencing cavern failure are discussed, and the number of cracks is quantified. Finally, it is found that the HDZ of the caverns is significantly reduced by applying a waterproof layer. The findings in this study have practical significance for predicting and improving the long-term stability of underground caverns in Longyou Grottoes under complex climatic conditions.

Influence of main operating parameters on the incineration characteristics of municipal solid waste (MSW)

To study the influence of the main operating parameters on the incineration characteristics of municipal solid waste (MSW), a 375 t/d mechanical grate incinerator is selected as the research object, and the effects of primary air temperature, secondary air arrangement, and grate speed on the MSW incineration process are simulated, and experimental tests are carried out under different primary air temperature and grate speed conditions. The results show that the relative errors between the measured and simulated values of the incinerator outlet O2 content and the measurement point temperature are within ±5% for all test conditions. When the primary air temperature increases from 423 K to 503 K, the position where the MSW incineration ends moves 3.32 m towards the front of the grate, and the moisture evaporation and fixed carbon combustion rates also increase, but the maximum volatile release rate and the optimal incineration condition of the MSW occur at the primary air temperature of 483 K. The increase in grate speed delays the incineration process of MSW and decreases the moisture evaporation rate and fixed carbon combustion rate, but it worsens the incineration effect of MSW. When the grate speed increases from 6.94 m/h to 13.88 m/h, the MSW incineration process is delayed by 3.20 m, and the moisture evaporation and fixed carbon combustion rates decrease by 43 kg·m−2·h−1 and 9 kg·m−2·h−1, respectively. To achieve the optimal operating conditions, the secondary air volume ratio of the front and rear arches is 1.59:1, the secondary air direction of the front arch is 40° and 60°, and that of the rear arch is 0° for the primary air temperature of 463 K and 483 K, respectively. This study can provide useful insights for optimizing the design and operation of mechanical grate incinerators.

Early-age inhomogeneous deformation of 3D printed concrete: Characteristics and influences of superplasticizer and water-binder ratio

3D printed concrete (3DPC) commonly experiences significant shrinkage along the printing direction (x-direction) at the early-age for its high cementitious material content, low water-binder ratio and formwork-free manufacturing process. This shrinkage with gradient along the vertical direction (z-direction) can cause interlayer slippage and further deformation within each filament. To investigate these early-age deformations and their dependence on materials, digital image correlation (DIC) was used to monitor the inhomogeneous deformation of 3DPC at the age of 0.5–6.5 h. It was found x-direction inhomogeneous shrinkage pattern is correlated with early-age hydration process and elastic modulus. After conducting mechanic analysis, it was found that an individual filament could be treated as a Winkler foundation beam with frictional moment, which can provide a semi-quantitative explanation of the phenomenon that the bottom filament shows significant downward deflection, while other layers show minimal upward deflection or almost no deflection. Additionally, the influence of superplasticizer and water-binder ratio on early-age inhomogeneous deformation was monitored. There exists an optimal dosage range for superplasticizer that ensures both better printing quality and lower x-direction shrinkage, shrinkage gradient as well as bottom layer deflection. With the same printing quality, early-age shrinkage, shrinkage gradient and the bottom layer deflection were reduced by adopting higher water-binder ratio. The influence of materials on the moisture evaporation rate and early-age strength was also measured and correlated with early-age x-direction shrinkage, shrinkage gradient of 3DPC and the extent of early-age bottom layer deflection.

Assessment of loess terraced slope erosion using unmanned aerial vehicle photogrammetry: Topographic and hydrological effects

AbstractTerraced slopes are widely used in the Loess Plateau to control gully erosion, yet their potential to induce new erosion patterns remains overlooked. Here we used unmanned aerial vehicle (UAV) photogrammetry to obtain centimeter‐resolution digital surface models (DSMs) and derived hydrological networks, slopes, aspects, and curvatures of the terraced slopes. Our analysis reveals terraces disrupted natural water pathways, spurring new rill formations during each rainy season—a process neglected by models. Intriguingly, despite gentler gradients, terraced slopes exhibited higher erosion rates than steeper gullies, with widespread rills on terrace ridges. Vegetation‐induced deposition surpassed erosion by 1.52 times, but moisture evaporation on sunny slopes limited plant growth and enhanced erosion. We propose targeted strategies tailored to these erosion mechanisms, including terrace redesign, runoff diversion, slope strengthening, and suitable vegetation, advancing sustainable land management. However, this study faces limitations due to the reliance on drone photogrammetry, which may be influenced by environmental factors like varying solar angles and vegetation growth, and the lack of extensive field validation to support the UAV‐derived data. Our study spotlights drone photogrammetry's potential for elucidating complex erosion dynamics on terraced slopes.

ТЕПЛОМАССООБМЕННЫЕ ПРОЦЕССЫ В ИСПАРИТЕЛЬНОМ БЛОКЕ ВОЗДУШНОГО ТЕПЛОВОГО НАСОСА

Heat pump installations and the possibility of their application in engineering systems are considered. This allows expanding significantly the possibilities of using renewable energy sources, as well as waste heat from various technological processes in engineering systems for creating a microclimate. Air heat pumps are the most promising, but their use in regions with a cold climate is limited due to condensation of moisture vapors on the cooling line of the evaporation unit with subsequent formation of ice, which reduces the efficiency of the installation. In this paper, an upgraded evaporative unit of an air heat pump with a MOVEBIT ice removal system is considered. Taking into account the design of the heat exchanger, which includes a magnetostrictive radiator unit, the influence of heat and mass transfer processes in the evaporation unit on the efficiency of the heat pump unit in a wide range of outdoor temperatures is considered. A criterion equation has been obtained for calculating the heat transfer coefficient in the evaporation unit depending on the hydrodynamic conditions of the process and the thermophysical parameters of the air environment. This equation allows to calculate the heating capacity and cooling capacity. In addition, to determine the coefficient of energy transformation of a heat pump installation at all stages of the life cycle of engineering systems. The dependence of the influence of temperature and relative humidity on the kinetics of ice formation is obtained. This provide calculation the operating time of the installation between the cycles of switching on the radiator to destroy the ice. Based on the research results, computer programs have been developed for controlling the main thermal parameters of an air heat pump with a MOVEBIT system and an electrical part of a magnetostrictive radiator in a wide temperature range.